PMart,
On your map, if you come out of the mouth of the Cowlitz and go out around Cottonwood Island, Prescott Beach is about 1/2 mile east on the Oregon side of the Columbia. Keep going east about another mile and cross back over to the Washington side and you will hit the Mouth of the Kalama. The Trojan plant will be right across the river from you. There you'd want to troll from just east of the green channel marker back towards the Cowlitz till you hit the deep hole in front of the big pier, staying in 15 - 30ft of water. Beaver / County line is west of your map. It is about a five mile run from the launch at willow grove, which is on the west side of Longview by Fisher Island.

If you ever see a Smokercraft Tracer with a 25hp Yami 4-stroke out there, say hi. I am usually at Sportsman (by Kalama) or down at Beaver.